Reference to Prior Application
This application is a continuation-in-part of patent application Ser. No. 700,976, filed Feb. 12, 1985, entitled Improved Distilling Apparatus, now abandoned which is a continuation-in-part of patent application Ser. No. 476,582, filed Mar. 18, 1983, now abandoned.
It is known that vapor compression provides an efficient means for evaporation for the desalination of sea water and brackish water. In the past, desalination systems have at the best obtained efficiencies in the range of sixty to seventy-five percent. If this efficiency can be increased to eighty-five to ninety percent, the cost for the desalination for an acre foot of water is significantly decreased.
The first vapor compression evaporators using mechanical compressors were built in Europe about 100 years ago. Since that time, thousands of mechanical vapor compression evaporators have been put into service around the world for desalting sea water and brackish water. Several hundred evaporators have been installed in the chemical process industries to concentrate solutions ranging from inorganic chemicals to temperature sensitive food products. The primary advantage of mechanical vapor compression evaporation over conventional single or multi-effect arrangements is far lower energy consumption. The price of oil and other energy sources in the past have been an increasing incentive to investigate vapor compression evaporation as a means of reducing energy usage and the energy contribution to product costs.
It is well known that liquid will stand freely within a vertical column, with the bottom of the column being open in a reservoir of the liquid and the top of the column being exposed to a vacuum. The free standing of the vertical column has to do with the air pressure being applied to the surface of the liquid reservoir. The density of the liquid determines the height of the standing of the liquid. For example, mercury will stand thirty inches. Similarly, a column of fresh water will stand approximately thirty-four feet. A column of salt water will stand approximately thirty-three feet, since the salt water is of a slightly greater density than the fresh water. Vapor of the liquid is collected in the vacuum located above the free standing column of liquid. In essence, the upper surface of the liquid boils.